Is a Small Amount of Radiation Bad for you?

Well, this question is hard to answer, and even harder to study. It is a contentions and continuously debated question in the field of radiation safety.

Low dose ionizing radiation is an interesting topic, but when you read this remember that these dose levels are far smaller than what we are normally dealing with in Radiotherapy. So this post is more pointed at a general radiation discussion rather than a Radiotherapy discussion.

Is a small amount of radiation bad for you?

The effects from high levels of radiation dose is known to be extremely bad. This has been seen by witness of radiation sickness of early scientists working on nuclear weapons and technologies. As well as survivors of atomic bombs and nuclear accidents.

Effects from early radiation therapy also pointed to high doses having bad effects. The need to shield healthy tissue throughout the radiotherapy process was identified through cancer survivors treated with these early technologies showing long term complications.

So it is clear that high doses of ionizing radiation is dangerous to our health.

But it is still unclear to scientists what the effects of low dose radiation is. Is is bad? Is it good?

So in radiotherapy and radiation protection we use models to predict the risk of inducing cancer from different levels of radiation exposure. The most commonly accepted model of radiation risk is the Linear No-Threshold Model. But lately there has been more and more debate about whether it holds at low doses. More research is questioning what happens at the low dose region. Studies have began to see whether low doses might be beneficial for us.

Linear No-Threshold Model

Generally, most people in the radiotherapy and radiation protection industry support the “Linear no-threshold model” (LNT) of radiation effects. The LNT model explains that less radiation is always better (see graph below).

Radiation Hormesis Model

There are other models that have traction as well. One of these other models is called the Radiation Hormesis Hypothesis. This model says that below a certain dose level radiation can stimulate your immune system, this is a very low dose level. The model basically says that low dose radiation is beneficial to you and has a lower cancer risk than higher doses. The rationale is that the radiation increase the rate of certain cell turnover involved in the immune system.

Super Linear Model

The super linear model is the opposite of radiation hormesis model. It suggests that low dose radiation has an increase cancer risk compared to medium radiation doses. This model hasn’t really made that much headway in the scientific community.

Is there a Scientific Consensus to radiation risk?

So as I mentioned earlier, the vast majority of evidence points to the Linear No Threshold model, but there have been studies showing evidence for both the superlinear and radiation hormesis more. Sometimes showing increased risk of cancer due to increased background radiation levels, and other times showing decreased risk of cancer with high background radiation levels.

Where does the Linear No-Threshold Model come from?

It is difficult to prove or disprove what happens in the low dose region- This is because there is limited data available. Most of the data used for these radiation effect models comes from radiation accidents and incidents. The largest data set come from atomic bomb survivors from the Hiroshima and Nagasaki atomic detonations. These are high dose situations.

Another reason why it is difficult is that the level of background radiation is different depending on where you live. Background radiation is between 1.3 mSv in Vancouver Canada and up to 240 mSv in Ramsar Iran, with a world average of 3 mSv per year. That’s a huge difference.

Just to give you some context on how low these doses are, you will have a 50% chance of surviving 4.5 Sv (4500 mSv) of radiation dose delivered to the whole body over a very short period of time, say a day. This is a huge amount compared to average yearly radiation dose. Even in Ramsar you would only receive 0.6 mSv a day, which is nowhere near 4500 mSv.

If you are curious about what the background radiation levels are in your area maybe you should get a radiation detector. This RADEX RD1503 is quite a neat one. It has been calibrated using a

Cesium-137 radioactive source. It is slightly expensive, but definitely better than some of the cheaper alternatives that don’t give accurate readings for low doses. Scientific equipment is always expensive!

So all the data we have is far higher in dose than the area we are interested in. The models used for low dose have been linearly extrapolated from this data. So the general trend for these cases is that the cancer risk increases proportionally with radiation dose. This line is then extrapolated back to lower doses.

The LNT model therefore assumes that a lot of radiation causes a lot of cancer, a medium amount of radiation causes a medium amount of cancer, and a low amount of radiation cause a low amount of cancer. So there is no threshold level where radiation is safe, there is always a risk however small of radiation induced cancer.

This model has been used for decades because it is best to assume that low dose radiation isn’t good for us. We should always be cautious when dealing with radiation.

Evidence for Hormesis

The evidence for the hormesis model hasn’t been huge, but there are some studies out there. It isn’t such a far fetched idea when you think about how many other so called hormetic effect there are in humans that have been proven.

An hormetic effect is one where there is a limit below which there is no harm, and at certain low levels there are beneficial effects.

This is very true for exercise- too much exercise can kill, but we all know it is beneficial. It has also been shown in other situations such as being in the cold, being exposed to toxins, and fasting. This seems to make the body over react to the small stress, improving the body’s means to deal with the stresses.

Low Dose Radiation Might Be Good

Recently, several low dose rate studies have been performed to determine if hormesis exists. Some studies in mice have shown that low dose exposure has a protecting effect. Showing a higher survival rate when later the mouse is exposed to a second dose of radiation. This suggests that the immune system has become better prepared to repair the damage.

Similar results have been seen for unborn mice who were exposed to radiation levels equivalent to the chernobyl accident. The radiation exposure did no harm to the mice’s health.

More strangely, there have been studies that show low dose radiation can help in complications from diabetes. They have shown that diabetic rats heal faster after they were dose with low dose radiation. Similarly, low dose radiation has shown to prevent kidney damage cause by diabetes.

All this does point to the LNT model being wrong at low doses. And it suggests that below a level certain dose level there may be benefits. But these studies are all done with animals, it would be nearly impossible to perform these controlled studies on humans.

Natural Population Sample Groups

However, natural studies can be done. One study is examining what low dose radiation dose to a population. Comparing two separate populations with different background radiation levels you can examine the difference in cancer incidence. Comparing cancer incidence in different states is a good tool- say compare a state where nuclear testing was done, or one with uranium mines, to a state with significantly lower background radiation. This has been used to show that there was a significantly lower lung cancer incidence in the states with higher background radiation.

This study by itself though is not proof for hormesis, there could be many other factors causing this correlation. Experts are still in agreement that the evidence is too thin to prove hormesis in humans. Many of the studies showing benefits do not account for the down sides of low dose radiation, such as induced cancer many years later.

Take the case of low dose radiation given to dogs, which showed that the dogs had an increased ability to repair DNA and

For instance, in experiments on low-dose radiation given to dogs over the course of their lifetimes, though the dogs showed increased DNA repair and could reproduce cells faster, they also showed a higher incidence of leukemia- a cancer of the blood.

Final Conclusion on weather a small amount of radiation is bad for you

Low dose radiation may be good for us.. We have evolved with a small amount of background radiation from the earth and space. This does damage some cells, but we have created systems to repair this damage throughout our evolution.

The believed that a small amount of radiation, slightly higher than background could be good for use comes from the belief that this will amp up the repair mechanisms. Afterwards, the body will be more protected from future radiation, the body’s defenses have been built up.

The believe that a small amount of radiation could be bad for use comes from the believe that even a small amount of radiation increases the risk of inducing a cancer many years later.

All this talk about low dose radiation is kind of relevant regarding the debate on whether or not low dose x-ray imaging is harmful to the patient. Certainly there should always be a justification to expose a patient to radiation. The benefits clearly outweighing the risks.

But the debate is still raging. Much more research is needed, especially the effects of low dose radiation to mammals.

Thank you for taking the time out of your day to read this post. As always I appreciate any comments, questions, or feedback. Comment below or message me directly.

And remember to subscribe to receive the next post! Just to re-iterate, we are specifically talking about Ionising radiation

Originally published at www.radicalradiationremedy.com on January 6, 2017.